On the development of novel gamma/gamma' two phase Fe-base superalloys - A novel high-temperature structural material beyond heat-resistant steel

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14546
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 30010:Crystal engineering-related
• Research Institution: Kyoto University
• Principal Investigator: Chen Zhenghao 京都大学, 工学研究科, 助教 (20889109)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 高温構造材料 / 二相超合金 / 力学特性 / 環境耐性 / Co2削減

Outline of Final Research Achievements

In the present study, we proposed a practical approach to design a novel Fe-base superalloy strengthened by L12-(Fe,Ni)3Ge in Fe-Ni-Ge and its alloyed multi-component system. The novel Fe-base superalloy exhibits a truly Ni-base superalloy-like gamma/gamma' two phase microstructure and is thus excepted for high-temperature structural use. We investigated the effects of alloying addition of Cr, Si, Al, W, Mo on the mechanical properties as well as the oxidation resistance of the alloy. We also found a way to reduce the use of the expensive metal Ge by substituting part of the Ge with Si.
On the other hand, however, the high-temperature strength, in particular higher than 750C is still a issue to be resolved, due to the decreasing of the gamma' strengthening phase at high temperatures.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

本研究は人類試料で最も汎用且つ廉価な構造材料「鉄」をベースに、高温構造材料として大成功を収めたNi基超合金の微細構造を再現させることで、廉価で高強度の新規高温構造材料の可能性を提示した。本研究で開発したプロトタイプ合金は、700℃の高温でも室温と同レベルの強度を有し、使用温度700℃、即ち火力発電の超超臨界(A-USC)条件を満たす可能性が現れた。学術的には、Ni基、Co基のほかにγ/γ'二相超合金を設計しうる新規の合金系を提案するとともに、社会的には、新規材料により現行する耐熱鋼を代替し、火力発電の効率向上および温室ガスの排出削減に貢献すると予測する。